reading-notes

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Authentication

Explain what a “Singleton” is (in Computer Science terms) ?

• A singleton is a class that allows only a single instance of itself to be created and gives access to that created instance.
• It is used in scenarios when a user wants to restrict instantiation of a class to only one object

Explain how the Singleton pattern can be used with Node modules, specifically with classes ?

• Node.js modules can behave like Singletons, but they are not guaranteed to be always singleton. There are two reasons for this and both are mentioned in the official Node.js documentation:

1. Node’s module caching mechanism is case-sensitive:

2. Modules are cached based on their resolved filename

• In Node.js, files and modules are in one-to-one correspondence.

• This object has two methods and an internal private variable called “value”.

If you were tasked with building a middleware system like Express uses, what approach might you take to construct/operate it?

• Create a new project and npm init it…
  npm init
npm install express --save

• Create server.js with following code:

  • const express = require('express');

  • const app = express();

  • ` app.get(‘/’, (req, res, next) => {<br> res.send(‘Welcome Home’);<br> });`
    

  • app.listen(3000);
• Run the server by node server.js

• local host: http://localhost:3000 »> should see “Welcome Home” printed in your browser.

• In Express, you can set up middleware to be “global” middleware; meaning it will be called for every incoming request.
  • app.use((req, res, next) => {
console.log(req);
next();
});
    

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Preparation Materials

Securing Passwords
Basic Auth
OWASP auth cheatsheet
bcrypt docs